Being mayor of New Orleans means taking up a lot of worthwhile fights. Put Mayor LaToya Cantrell’s ongoing showdown with the tourism interests, aimed at diverting some of the industry’s revenue to badly needed infrastructure maintenance and improvements, in that bucket.

But it also means avoiding the unnecessary battles. Cantrell’s handling of a policy change involving widely detested traffic cameras is Exhibit A.

As many people found out via an unexpected ticket in their mailbox, the Cantrell administration quietly changed course and reduced the longstanding buffer between the posted speed limit, in school zones and elsewhere, and the threshold for invoking a significant traffic fine. By declining to give motorists fair warning, Cantrell has created a needless mess.

It’s not a mess because government doesn’t have the right to penalize people who violate the law. It absolutely does.

It’s not a mess because drivers caught in the sting don’t care about kids’ safety, Cantrell’s now-stated reason for making the change. I would wager that most of them care deeply, but that they also understand that the difference between traveling 24 and 26 miles per hour in a 20 mph school zone isn’t likely to impact public safety to any appreciable measure.

It’s not even a mess because Cantrell campaigned as a critic of traffic cameras, leading many voters to believe she found them as aggravating as they did. Although her position on taking them down shifted during the campaign, her tone didn’t.

It’s a mess because the administration didn’t play it straight with residents at the outset, and continued to dodge even after the entirely predictable public blowup.

The recent change to the rules for New Orleans' traffic cameras that has infuriated some residents was discussed at length by members of Mayor…

Ironically, new details show that officials actually did consider informing the public of the coming policy change. According to internal communications obtained by The New Orleans Advocate through a public records request, some aides argued in favor of a public relations campaign. “Behavioral adjustments" would come "as long as drivers are aware of the impending change," wrote city economist Deborah Vivien to Cantrell's top deputies, including Chief Administrative Officer Gilbert Montaño and Public Works Director Keith LaGrange.

But no such notice occurred.

Also circulating around the administration at the time was an internal analysis showing how much more money the city could raise by lowering the threshold. It projected that the change in school zone enforcement could result in up to 100,000 additional tickets and as much as $7.5 million in additional revenue. And indeed, following the furtive change in February, 79 percent more tickets were issued than a month earlier, according to nola.com.

Belatedly, Cantrell has gone public heartily defending the move, chalking it up entirely to public safety and concern for children. Monday morning, she appeared before the a City Council committee and argued that publicizing the new policy would have somehow encouraged violators rather than giving everyone notice that they need to slow down.

I guess people are supposed to take it on faith that nobody considered the inevitable revenue bump. Some of that extra money is surely coming from struggling residents for whom an unexpected $75 or higher expense is difficult to absorb, a concern she acknowledged back during the campaign.

The influx in cash is likely to be short-lived, as people come to understand the change and adjust their driving habits accordingly. The sore feelings over what certainly comes off as a money grab — particularly given Cantrell’s emphasis on the issue during the campaign — will probably linger much longer, and understandably so.

That’s the downside when a mayor doesn’t clearly explain her thinking and her motives. When you leave things open to interpretation, people will be draw their own conclusions.